The mechanization level of various areas is improved constantly with the constant development of our society; wherein, the sheet material separation technique for separating sheet materials, such as banknote, paper sheet, bill and the like, one by one is also greatly developed. Automated sheet material separation mechanisms are also more and more widely used in this technical area, for example, sheet material separation mechanisms are widely used in a cash access apparatus of an automatic teller machine (ATM), an bank cash/note sorting apparatus, a printer, a duplicator, a paper sheet separation apparatus for a printing press.
The existing sheet material separation mechanism for separating bank notes, paper sheets and bills generally comprises a frame, a plurality of conveying wheels, a separation wheel, a reversal wheel, a driving component, an eccentric adjustment device and a one-way bearing. The plurality of conveying wheels are directly rotatablely mounted on the frame by means of a conveying shaft, and may rotate with respect to the frame together with the conveying shaft; the separation wheel is directly rotatablely mounted on the frame by means of a separation shaft, and may rotate with respect to the frame together with the separation shaft; the reversal wheel is mounted on the frame by means of a reversal shaft and the eccentric adjustment device. The reversal wheel and the separation wheel are spaced apart by a predetermined distance to form a separating gap. The friction force generated between the separation wheel and a sheet material to be separated is greater than the friction force generated between the reversal wheel and the sheet material to be separated. The driving component comprises an electromotor and several synchronous belts, the electromotor drives the separation shaft, the conveying shaft and the reversal shaft to rotate via the synchronous belts, and consequently drives the separation wheel, the conveying wheel and the reversal wheel to rotate; at the same time, the driving component makes the separation wheel rotate in the same rotation direction as that of the conveying wheel, and makes the reversal wheel rotate in an opposite rotation direction to that of the separation wheel. The eccentric adjustment device comprises an eccentric adjustment plate and an eccentric plate, the eccentric plate and the eccentric adjustment plate are mounted respectively on the inner and outer sides of the frame through a fixing hole on the frame. The eccentric plate is mounted on the inner side of the frame, and comprises an outer ring and an inner ring suitable for moving within the outer ring. Inside the inner ring the one-way bearing is pressed; the reversal shaft is fitted into the one-way bearing, and the one-way bearing controls the rotation direction of the reversal shaft.
During the assembly process of the aforesaid sheet material separation mechanism, the eccentric adjustment plate is rotated to drive the inner ring of the eccentric plate to move within the outer ring, and then to drive the reversal shaft to move via the built-in one-way bearing, and consequently to drive the reversal wheel to move up and down so as to allow for adjusting the size of the separating gap. After the size of the separating gap is adjusted according to the regulation, the eccentric plate and the eccentric adjustment plate of the eccentric adjustment device are fixed on the frame by a fastening bolt, thereby the inner ring and the outer ring of the eccentric plate are fixed; after the inner ring of the eccentric plate is fixed, the separating gap between the separation wheel and the reversal wheel cannot be further adjusted.
When a separating operation is conducted using the sheet material separation mechanism, sheet materials to be separated are firstly put on the conveying wheel, then the sheet materials are conveyed to the separating gap between the separation wheel and the reversal wheel by the conveying wheel. Since the rotation direction of the reversal wheel is opposite to that of the separation wheel and the friction force applied by the separation wheel on the sheet material contacting with the separation wheel is greater than the friction force applied by the reversal wheel on the sheet material contacting with the reversal wheel, the sheet material contacting with the separation wheel will pass through the separating gap under the action of the friction force generated by the separation wheel, and be further conveyed to the transmission passage for the next operation; at the same time, other sheet materials are stopped outside the separating gap by the reversal wheel, the separation wheel and the reversal wheel cooperate with each other so that only one piece of the sheet material passes through the separating gap at a time.
From the above description, it can be seen that, in the prior art, the size of the separating gap is adjusted before separating the sheet material, and the eccentric adjustment device is fixed after the adjustment is finished; here, the inner ring of the eccentric plate is fixed and cannot move, the separating gap between the reversal wheel and the separation wheel is constant, the constant separating gap can only be suitable for sheet materials with fixed thickness, when there are old and new and/or different kinds of sheet materials with difference thickness, a separation failure easily occurs. In particular, the sheet material cannot go into the separating gap when the thickness of sheet material to be separated is greater than the separating gap, which results in a failure of separation; when the thickness of sheet material is smaller than the separating gap, plural pieces of the sheet material may synchronously go into the separating gap, thereby, not only the purpose that the sheet materials are separated one by one cannot be achieved, but also the separation wheel may be stuck due to an excessively large frictional resistance, thereby the whole sheet material separation mechanism cannot operate properly.
Therefore, it is necessary to provide an improved sheet material separation mechanism to overcome the shortcomings described above.